1 the function f is defined for all positive integers n by the following rule. f(n) is the number of positive integers each of which is less than n and has no positive factor in common with n other than 1. If p is any prime number then f(p)=
A p-1 B p-2 C (p+1)/2 D (p-1)/2 E 2 answer:A
这题没怎么看明白，所以算了半天也没算清楚
2 一个数列｛－10，－6，－5，－4，－2.5，－1，0，2.5，4，6，7，10｝，任取一个数，使得(x-5)(x+10)(2x-5)=0成立的概率是多少？
A 1/12 B 1/6 C 1/4 D 1/3 E 1/2 answer: B
不太明白，要让这个等式成立应该是有3个数都符合条件，5，－10， 2.5，这样说来，概率难道不是3/12=1/4吗？
3 R bought two kind of candy bars, C and T, that came in packages of 2 bars each. He handed out 2/3 of C bars and 3/5 of the T bars. Howmany packages of C bars did R buy?
1) R bought 1 fewer package of C bars than T bars
2) R handed out the same number of each kind of candy bars
answer: C
不明白packages和 number of bars是什么关系？
完了完了，我脑子是不是进水了？？？这么多题都不会！！
恳请大家帮忙！！！谢谢大家了！！ | 
